1. Field of the Invention
The present invention relates to a runflat tire, more particularly to a sidewall structure capable of improving ride comfort and weight reduction without deteriorating runflat performance.
2. Description of the Related Art
A runflat tire which is provided in each sidewall portion with a sidewall reinforcing rubber having a substantially crescent shape has been proposed, for example as shown in Japanese Patent Publications of JP-2002-301911A1, JP-2994989B1 and JP-2005-67315A1. The crescent-shaped sidewall reinforcing rubber is disposed axially inside the carcass in order to increase the bending rigidity of the tire sidewall portion to thereby support the tire load during runflat conditions such as puncture.
In this structure, however, as the bending rigidity is increased always, namely, during normal running and runflat conditions, deterioration in the ride comfort during normal running is inevitable. Further, a fuel efficiency of a car with runflat tires tends to become worse, since the sidewall reinforcing rubber makes tire weight increase.